In the present systems for transporting goods in cardboard boxes or containers, where both resistance to relative moisture and contact with fluids are a major factor, there is in addition to the condition of being non-returnable and/or capable of being in direct contact with food products, the issue of structural strength and international regulations in this respect.
Typically, cardboard boxes that are either made from a corrugated or a compact material for these purposes, though they have the advantage of being transported in a flat or unassembled condition to the areas where they shall subsequently be filled, thus saving transport space, involve the disadvantage of losing their structural strength in the presence of humidity. To overcome this drawback these cardboard boxes are sprayed or primed at present with paraffins or waxes in an attempt to keep moisture from permeating the surface of their inner and outer faces. It can be said in this regard that it is not possible to seal the perimetrical edges or faces of the cardboard by these processes, and moisture usually penetrates the cardboard box through said faces and edges, weakening at the same time its structure. The structure of pallets with this type of containers run a high risk of collapse of the load when subjected to these environmental conditions.
The standards being implemented at present by countries that have advanced with regard to contact of the containers with foodstuffs are in the line of banning the use of these treatments of either paraffin, wax or silicone sprayed over the cardboard, thereby further exacerbating the problem. This increases the need for a reliable transport solution without risk to health and complying with all the regulations.
Furthermore, these standards tend to support the ecology, renewability and biodegradability of “non returnable” single-use containers that are in contact with food products.
Countries such as the United States of America and the European Union are placing all kinds of obstacles and problems on food imports contained in non-returnable and single use containers where the container does not meet these expectations.
Likewise analysis of plastic containers for these same purposes shows that these are also being banned because they are difficult to recycle owing to their non-returnable condition with the imposition of economic quotas and because of their structure usually manufactured by injection molding, which makes them very difficult to transport in a deployed or flat format from the manufacturing plant to the filling facility, thus increasing costs as air represents a major part of the transported volume.
The wooden boxes regularly used for this purpose also comprise components that are aggressive to the environment, are not safe and are damaging to health, such as staples and nails. These are also being banned by the present regulations due to their high degree of oxidation in high humidity environments and to the danger they present when users handle them.
Patent EP 1 834 884 proposes a mono-material container for horticultural use that, to some extent, aims to solve the problems of the prior art. However, it has the disadvantage that as its parts are obtained by a die or saw cutting process, the perimetrical faces of said parts are left with its internal fibers exposed and physically degraded after impact or cutting, making them lose their normal density and causing them likewise to easily lose structural stability at their contours due to the sponge-like effect or response that takes place throughout the cutting perimeter of each component, leaving them prone to moisture penetration as in the case of cardboard.
As said container analyzed is not provided with fastening elements that are subject to tensile work, and as the elements that form said container are supported structurally joined exclusively by direct compression work of fully rigid male part flaps or flukes over female part slots, these elements get weakened, degraded and softened by the penetration of moisture inside and fail to correctly perform their structural setting function. Moreover, said container requires the use of additional slits and aeration holes to make its ventilation inside easier further increasing its structural weakness because it provides a greater number of sides through which moisture may penetrate.
Fastening elements called clips or flexible tabs are already available in the market, these elements being subject to tensile strength for securing the assembly of the different elements with each other. These clips are usually made from injection molded plastic materials and include different ribs and/or flexible braces, which as flukes, once inserted as arrows or tabs harpoon prongs prevent their return or withdrawal from the place they are lodged in. However, elements of this type can not be developed in the same way when using ecologic materials such as wood fibers, because they are not able to withstand high tensile efforts owing to their low density and loss of strength in the contours when said flukes or claws are cut with saws or dies.
Therefore, the known prior art presents the main drawback of the structural weakness of existing containers made from cardboard or wood fibers when subjected to the inner pressure of the contained load, either due to compression of the contents or due to inner displacement thereof during transport, resulting in subsequent outward sagging of the sides as, for example, it occurs with bulk packaging where the contents in the interior subjects the container sides to high pressures that generate said outward sagging effect, which directly leads to contact reduction in the outer perimeter of the vertically stacked containers. The load on the pallets is thus made unstable when said contact is reduced, and is likewise reduced the capacity of the containers placed on the lower layers and supporting all the weight of the upper layers or rows to withstand vertical compression. This vertical compression effect is translated into a logical increase of said sagging or horizontal deformation, generating a chain effect that ends up destroying the containers in the lower rows and spoiling their contents.
Therefore, there is still in the art a need for a self-assemblable container that provides at least a partial solution to the above described problems, a greater ease of assembly of the container, with fewer mechanical operations for its manufacture than previously known containers, reducing at the same time the costs of production and assembly thereof.